Ultra-wideband circularly polarized patch antenna

Abstract

The invention belongs to the technical field of antennas, and relates to an ultra-wideband circularly polarized patch antenna, which comprises a dielectric substrate and a radiation patch arranged on the dielectric substrate, the radiation patch comprises a feed branch knot, a coupling branch knot and a grounding branch knot with an annular structure; the feed branch comprises a first part of a rectangular strip structure, a second part of the rectangular strip structure and a third part of a U-shaped structure; one end of the first part is connected with the inner ring of the grounding branch, and the other end is connected with the middle of the third part; the second part is connected with the middle part of the first part, so that the second part and the first part form a T-shaped structure; the open end of the third part faces the coupling branch knot and is arranged at an interval with the coupling branch knot, so that coupling current is generated between the feed branch knot and the coupling branch knot; one end of the coupling branch is connected with the inner ring of the grounding branch. According to the invention, ultra wide band and circular polarization can be realized.

Description

Technical Field

[0001] The present application relates to the field of antenna technology, and in particular to an ultra-wideband circularly polarized patch antenna. Background Art

[0002] In the development of satellite navigation systems in recent years, the Global Navigation Satellite System (GNSS) has gradually become a core component of various positioning, navigation and timing applications. As a global satellite navigation system independently developed by China, the BeiDou system has the characteristics of high precision, multi-band, global coverage, etc., and has been widely used in many industries. With the development of science and technology, the integration of navigation systems has become more and more common. In order to ensure that these devices can stably and accurately receive BeiDou satellite signals, antenna technology has become one of the key links.

[0003] However, many existing antennas only support single or narrow frequency bands and cannot cover all frequency bands of the BeiDou system, resulting in unstable or lost signal reception. Circularly polarized antennas are widely used in satellite communication systems because they can effectively reduce interference from multipath effects.

[0004] Based on this, how to realize wideband circularly polarized antenna has gradually become a research hotspot. Summary of the invention

[0005] Based on this, it is necessary to provide an ultra-wideband circularly polarized patch antenna to address the above technical problems, which can achieve ultra-wideband and circular polarization.

[0006] An ultra-wideband circularly polarized patch antenna, comprising: a dielectric substrate and a radiation patch arranged on the dielectric substrate; The radiation patch includes: a feeding branch, a coupling branch and a grounding branch of a ring structure; The feeding branch comprises: a first part of a rectangular strip structure, a second part of a rectangular strip structure and a third part of a "U"-shaped structure; one end of the first part is connected to the inner ring of the grounding branch, and the other end is connected to the middle of the third part; the second part is connected to the middle of the first part, so that the second part and the first part form a "T"-shaped structure; the open end of the third part faces the coupling branch and is spaced apart from the coupling branch, so that a coupling current is generated between the feeding branch and the coupling branch; One end of the coupling branch is connected to the inner ring of the grounding branch.

[0007] In one embodiment, the coupling branch comprises: a first component of a rectangular strip structure, a second component of an "L"-shaped structure, and a third component of a rectangular strip structure; One end of the first component is connected to the inner ring of the grounding branch; One end of the second component is connected to one end of the first component and is spaced apart from the grounding branch; One end of the third component is connected to the other end of the second component, and the other end of the third component is arranged crosswise with the other end of the first component; The first component, the second component and the third component enclose a rectangular space.

[0008] In one embodiment, the other end of the third component is bent toward one end of the first component, so that the third component forms a step-shaped structure, and a groove is formed at a corner end of the rectangular space.

[0009] In one embodiment, the second component comprises: a first section and a second section; One end of the first segment is connected to one end of the second segment; The other end of the first section is connected to the first component, and the first section is arranged parallel to the inner ring of the grounding branch; The other end of the second section is arranged at the central position of the grounding branch and extends to the middle of the opening of the "U"-shaped structure.

[0010] In one embodiment, the grounding branch comprises: a first component, two second components and a third component; The two ends of the first member are respectively connected to one corresponding end of the second member, and the two ends of the third member are respectively connected to the other corresponding end of the second member, so that the grounding branch forms a rectangular ring structure; Two symmetrical through grooves are provided in the middle of the third component, so that the third component is divided into a first part, a second part and a third part which are arranged at intervals, and the second part is connected to the feeding branch. In one embodiment, the first portion and the third portion are symmetrically arranged on both sides of the second portion, and the width of the first portion is greater than that of the second portion, so that the third component forms an inverted isosceles trapezoidal groove at the midpoint of the inner ring of the grounding branch.

[0011] In one embodiment, the feeding branch and the coupling branch have the same area.

[0012] In one embodiment, the distance between the feeding branch and the coupling branch is less than 1% of the length of any side of the grounding branch.

[0013] In one embodiment, the ground branch is connected to an outer conductor of the connector, and the first portion of the feeding branch is connected to an inner conductor of the connector to implement coplanar waveguide feeding.

[0014] In one embodiment, the dielectric substrate is made of flexible material to make the antenna wearable.

[0015] The above-mentioned ultra-wideband circularly polarized patch antenna is designed with a feeding branch, a coupling branch and a grounding branch. The current is coupled from the third part of the feeding branch to the coupling branch, and after passing through the first component, the second component and the third component of the coupling branch, it finally flows to the outer floor branch and completes the radiation to form a complete circular current path, thereby realizing the normal operation of the antenna. The antenna has an ultra-wide operating frequency band, an ultra-wide axial ratio bandwidth and an ultra-wide circular polarization performance, which can cover multiple Beidou frequency bands, thereby enhancing its compatibility and stability with satellite signals, and can adapt to different bending shapes of the human body, maintain high signal reception performance in a variety of postures, and have a low specific absorption rate and good wearing comfort, meeting the application needs of the Beidou satellite navigation system in the field of wearable devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of an ultra-wideband circularly polarized patch antenna in one embodiment; Figure 2 A schematic diagram of the structure of an antenna feeding branch in one embodiment; Figure 3 A schematic diagram of the structure of an antenna coupling branch in one embodiment; Figure 4 A schematic diagram of the structure of an antenna grounding branch in one embodiment; Figure 5 is a dimensional diagram of an antenna in one embodiment; Figure 6 is a front view of an antenna in one embodiment; Figure 7 is a physical side view of an antenna in one embodiment; Figure 8 A diagram of a darkroom environment where an antenna is located in one embodiment; Fig. 9 is a comparison diagram of the simulation and actual measurement results of the S11 and axial ratio of the antenna in one embodiment; Fig.10 A comparison diagram of simulation and actual measurement of the antenna directional pattern at 1575.45 MHz in one embodiment; Fig.11 A comparison diagram of simulation and actual measurement of the antenna directional pattern at 1176.45 MHz in one embodiment; Fig.12 A comparison diagram of simulation and actual measurement of the antenna directional pattern at 1268.52 MHz in one embodiment; Fig.13 is a wearable schematic diagram of an antenna in one embodiment; Fig.14This is a diagram of S11 measured results when the antenna is attached to the left shoulder of a human body in one embodiment; Fig.15 It is a schematic diagram of SAR distribution simulation of the Beidou system (BDS) of the antenna in an embodiment when worn on the right shoulder at frequencies B1 (1575.42 MHz), B2 (1176.45 MHz) and B3 (1268.52 MHz).

[0017] Reference numerals: Feed branch 1; Part 11; Part 2 12; Part 3 13, Article 1 131, Article 2 132, Article 3 133; Coupling branch 2; A first component 21; a second component 22, a first section 221, a second section 222; a third component 23; Ground branch 3; The first component 31 ; the second component 32 ; the third component 33 , the first portion 331 , the second portion 332 , and the third portion 333 . DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0019] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0020] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, etc., unless otherwise clearly and specifically defined.

[0021] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0022] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0023] The present application provides an ultra-wideband circularly polarized patch antenna, such as Figures 1 to 4 As shown, in one embodiment, it includes: a dielectric substrate and a radiation patch. The dielectric substrate is a plate-like structure and provides support for the radiation patch.

[0024] Preferably, the dielectric substrate uses a flexible material so that the antenna can bend and fit the human body surface to form a flexible wearable antenna to meet the needs of wearable devices. Compared with traditional antennas using hard materials or rigid structures in the prior art, flexible wearable antennas can adapt to the natural curves and movement characteristics of the human body and are suitable for long-term wearing without affecting the performance of the antenna itself.

[0025] The radiation patch is arranged on a dielectric substrate and comprises a feeding branch, a coupling branch and a grounding branch.

[0026] The feeding branch is arranged inside the grounding branch and connected to the inner ring of the grounding branch. The feeding branch includes: a first part, a second part and a third part; the first part is a rectangular strip structure, one end of which is connected to the inner ring of the grounding branch and the other end is connected to the middle of the third part to perform impedance matching and optimize circular polarization performance; the second part is a rectangular strip structure, which is connected to the middle of the first part so that the second part and the first part form a "T"-shaped structure as a whole to perform impedance matching and optimize broadband characteristics; the third part is a "U"-shaped structure, with an open end facing the coupling branch and spaced apart from the coupling branch so that a coupling current is generated between the feeding branch and the coupling branch.

[0027] The coupling branch is arranged inside the grounding branch and is connected to the inner ring of the grounding branch.

[0028] The grounding branch has a ring structure.

[0029] Preferably, the areas of the feeding branch and the coupling branch are equal to each other, so as to improve the axial ratio bandwidth.

[0030] Further preferably, the distance between the feeding branch and the coupling branch is less than 1% of the length of any side of the grounding branch, so as to improve the coupling effect between the feeding branch and the coupling branch, and improve the impedance matching effect between the feeding branch and the antenna, thereby further improving the bandwidth and achieving a wider ultra-wideband.

[0031] Further preferably, the third part includes: a first strip, a second strip and a third strip, and the first strip, the second strip and the third strip are all rectangular structures; one end of the first strip is vertically connected to one end of the third strip, and the other end extends toward the coupling branch; one end of the second strip is vertically connected to the other end of the third strip, and the other end extends toward the coupling branch; one end of the third strip is connected to the first strip, and the other end is connected to the second strip; the distance between the first strip and the coupling branch is smaller than the distance between the second strip and the coupling branch, and the length and width of the first strip are both smaller than the second strip, so as to improve the coupling effect between the feeding branch and the coupling branch, make the coupling strength between the first strip and the second strip and the coupling branch consistent, and form a 90° phase difference, so as to achieve better circular polarization performance.

[0032] More preferably, the ground branch serves as a ground plane, the ground branch is connected to an outer conductor of a connector (eg, an SMA connector), and the first portion of the feeding branch is connected to an inner conductor of the connector to implement coplanar waveguide (CPW) feeding and achieve miniaturization.

[0033] In another embodiment, the coupling branch includes: a first component, a second component and a third component; the first component, the second component and the third component are uniform strip structures of equal width and enclose a rectangular space.

[0034] The first component is a rectangular strip structure, one end of which is connected to the inner ring of the grounding branch, and the other end of which extends toward the inside of the grounding branch.

[0035] The second component is an "L"-shaped strip structure, one end of which is connected to one end of the first component and is spaced apart from the grounding branch, and the other end is connected to the third component.

[0036] The third component is a rectangular strip structure, one end of which is connected to the other end of the second component, and the other end of which is cross-arranged with the other end of the first component.

[0037] Preferably, the other end of the third component is bent toward one end of the first component so that the third component forms a stepped structure, and a groove is formed at a corner end of the rectangular space to reduce the axial ratio and improve the circular polarization performance.

[0038] Further preferably, the second component includes: a first section and a second section. One end of the first section is connected to one end of the second section; the other end of the first section is connected to the first component, and the first section is arranged parallel to the inner ring of the grounding branch; the other end of the second section is arranged at the central position of the grounding branch and extends to the middle of the opening of the "U"-shaped structure to improve the impedance matching effect.

[0039] In another embodiment, the grounding branch includes: a first component, two second components and a third component; the first component, a second component, the third component and another second component are connected end to end so that the grounding branch forms a rectangular ring structure.

[0040] The first component is a rectangular structure, and two ends thereof are respectively connected to a corresponding end of the second component.

[0041] The second component is a rectangular structure, one corresponding end of which is connected to two ends of the first component, and the other corresponding end of which is connected to two ends of the third component.

[0042] The third component is a rectangular structure, with its two ends connected to the other corresponding ends of the second component respectively, and two symmetrical through grooves are provided in the middle to divide the third component into a first part, a second part and a third part which are arranged at intervals, wherein the second part is connected to the feeding branch.

[0043] Preferably, the first part and the third part are symmetrically arranged on both sides of the second part, and the width of the first part is greater than that of the second part, so that the third component forms an inverted isosceles trapezoidal groove at the midpoint of the inner ring of the grounding branch to achieve better impedance matching and reduce the S11 of the antenna.

[0044] Further preferably, the coupling branch is connected to the second component of the grounding branch to form a biased structure, which is conducive to achieving right-hand circular polarization.

[0045] More preferably, the first member, the second member, the first portion of the third member and the second portion of the third member have different widths to achieve better circular polarization and a wider axial ratio bandwidth.

[0046] The above-mentioned ultra-wideband circularly polarized patch antenna is designed with a feeding branch, a coupling branch and a grounding branch. The current is coupled from the third part of the feeding branch to the coupling branch, and after passing through the first component, the second component and the third component of the coupling branch, it finally flows to the outer floor branch and completes the radiation to form a complete circular current path, thereby realizing the normal operation of the antenna. The antenna has an ultra-wide operating frequency band, an ultra-wide axial ratio bandwidth and an ultra-wide circular polarization performance, which can cover multiple Beidou frequency bands, thereby enhancing its compatibility and stability with satellite signals, and can adapt to different bending shapes of the human body, maintain high signal reception performance in a variety of postures, and have a low specific absorption rate and good wearing comfort, meeting the application needs of the Beidou satellite navigation system in the field of wearable devices.

[0047] In a specific embodiment, the dielectric substrate is made of polyimide (PI) material with a dielectric constant of 3.5 and a thickness of 0.2 mm; the radiation patch is loaded on the dielectric substrate with a copper foil material. The overall size of the antenna is 77.9 mm×73.2 mm×0.2 mm.

[0048] like Figure 5 The dimensions shown in the figure are as follows: W=73.9mm, L=77.2mm, W1=7mm, W2=4mm, W3=2mm, W4=5mm, W5=4mm, W6=3mm, W7=3mm, L1=9mm, L2=7mm, L3=11mm, L4=11.7mm, L5=10.6mm, L6=12mm, L7=24mm , L8=15mm, L9=17.1mm, L10=13.3mm, L11=19mm, L12=14.3mm, L13=18.5mm, L14=6.5mm, L15=55.2mm, L16=7mm, L17=5.9mm, S=33mm, g=0.2mm, g1=0.6mm.

[0049] like Figure 6 to Figure 7 As shown, the antenna is physically manufactured based on standard PCB manufacturing with soldering and assembly procedures.

[0050] like Figure 8 The anechoic chamber environment shown uses the 3D electromagnetic simulation software CST Studio Suite to simulate and test the above antenna.

[0051] like Fig. 9The comparison results of the simulation and measurement of the S11 and axial ratio of the antenna shown in the figure show that the measured S11 curve is lower than -10dB in the 1100MHz-2300MHz frequency band, and the general trend of the measured S11 curve is consistent with the simulation result, and the measured S11 in the 1400MHz-2300MHz frequency band is better than the simulation result. At the same time, the measured axial ratio curve is basically consistent with the simulated axial ratio curve, and the measured 3dB axial ratio working bandwidth is about 1100MHz-1700MHz.

[0052] like Figures 10 to 12 The comparison results of the simulation and measurement of the antenna (the actual object is in an unbent state) at different frequencies show that the measured RHCP directional pattern curve is basically the same as the simulated RHCP directional pattern curve. Figure 1 However, the measured RHCP gain is slightly smaller than the simulated RHCP gain, which is more obvious in the directional pattern result at 1575.45MHz. At this time, the measured RHCP gain is about 1dB lower than the simulated RHCP gain. This is due to the precision error in manufacturing and the error caused by testing (including the errors in reading the directional pattern test data and the secondary calculation of the gain).

[0053] like Fig.13 Wearable schematic of the antenna shown, with the antenna attached to the right shoulder of a human body.

[0054] like Fig.14 The S11 measured results of the antenna attached to the left shoulder of a human body are shown in the figure. In the range of 1150-2170MHz, the S11 curve remains below -10dB, effectively covering all major navigation frequency bands. This shows that bending the antenna and attaching it to the human body does not affect its good performance.

[0055] like Fig.15 The diagram shows the simulation of the SAR distribution of the BeiDou system (BDS) of the antenna shown in the figure at the frequencies B1 (1575.42MHz), B2 (1176.45MHz) and B3 (1268.52MHz) (average mass is 1.0 g) worn on the right shoulder. SAR is the simulated specific absorption rate of radiation, which refers to the energy absorbed by unit mass of human tissue. It is an important factor for wearable antennas. The maximum SAR values ​​of B1, B2 and B3 antennas are 0.801 W / kg, 0.477 W / kg and 0.555 W / kg respectively. All SAR values ​​are within the internationally prescribed human safety limit of 1.6 W / kg, meet international standards and have power safety.

[0056] In summary, the working bandwidth of the antenna of the present application is 1100-2300 MHz, the relative impedance bandwidth is 70.6%, the axial ratio (AR) bandwidth is 1100-1700 MHz, and the axial ratio relative bandwidth is 42.9%. It has an ultra-wide working frequency band and axial ratio bandwidth, and is lightweight and portable. It can adapt to different bending shapes of the human body and maintain good radiation characteristics under various bending conditions. It has broad application prospects in the Beidou satellite navigation system and wearable device fields.

[0057] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0058] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. An ultra-wideband circularly polarized patch antenna, characterized in that: include: A dielectric substrate and a radiation patch arranged on the dielectric substrate; The radiation patch includes: a feeding branch, a coupling branch and a grounding branch of a ring structure; The feeding branch comprises: a first part of a rectangular strip structure, a second part of a rectangular strip structure and a third part of a "U"-shaped structure; one end of the first part is connected to the inner ring of the grounding branch, and the other end is connected to the middle of the third part; the second part is connected to the middle of the first part, so that the second part and the first part form a "T"-shaped structure; the open end of the third part faces the coupling branch, and is spaced apart from the coupling branch, so that a coupling current is generated between the feeding branch and the coupling branch; One end of the coupling branch is connected to the inner ring of the grounding branch.

2. The ultra-wideband circularly polarized patch antenna according to claim 1, characterized in that: The coupling branch comprises: a first component of a rectangular strip structure, a second component of an "L"-shaped structure, and a third component of a rectangular strip structure; One end of the first component is connected to the inner ring of the grounding branch; One end of the second component is connected to one end of the first component and is spaced apart from the grounding branch; One end of the third component is connected to the other end of the second component, and the other end of the third component is arranged crosswise with the other end of the first component; The first component, the second component and the third component enclose a rectangular space.

3. The ultra-wideband circularly polarized patch antenna according to claim 2, characterized in that: The other end of the third component is bent toward one end of the first component, so that the third component forms a step-shaped structure and a groove is formed at one corner end of the rectangular space.

4. The ultra-wideband circularly polarized patch antenna according to claim 3, characterized in that: The second component includes: a first section and a second section; One end of the first segment is connected to one end of the second segment; The other end of the first section is connected to the first component, and the first section is arranged parallel to the inner ring of the grounding branch; The other end of the second section is arranged at the central position of the grounding branch and extends to the middle of the opening of the "U"-shaped structure.

5. The ultra-wideband circularly polarized patch antenna according to any one of claims 1 to 4, characterized in that: The grounding branch comprises: a first component, two second components and a third component; The two ends of the first member are respectively connected to one corresponding end of the second member, and the two ends of the third member are respectively connected to the other corresponding end of the second member, so that the grounding branch forms a rectangular ring structure; Two symmetrical through grooves are provided in the middle of the third component, so that the third component is divided into a first part, a second part and a third part which are arranged at intervals, and the second part is connected to the feeding branch.

6. The ultra-wideband circularly polarized patch antenna according to claim 5, characterized in that: The first part and the third part are symmetrically arranged on both sides of the second part, and the width of the first part is greater than that of the second part, so that the third component forms an inverted isosceles trapezoidal groove at the midpoint of the inner ring of the grounding branch.

7. The ultra-wideband circularly polarized patch antenna according to any one of claims 1 to 4, characterized in that: The feeding branch and the coupling branch have the same area.

8. The ultra-wideband circularly polarized patch antenna according to any one of claims 1 to 4, characterized in that: The distance between the feeding branch and the coupling branch is less than 1% of the length of any side of the grounding branch.

9. The ultra-wideband circularly polarized patch antenna according to any one of claims 1 to 4, characterized in that: The grounding branch is connected to the outer conductor of the connector, and the first part of the feeding branch is connected to the inner conductor of the connector to realize coplanar waveguide feeding.

10. The ultra-wideband circularly polarized patch antenna according to any one of claims 1 to 4, characterized in that: The dielectric substrate is made of flexible material to make the antenna wearable.

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